Preheat the oven to 450ºF. Put a large cast-iron frying pan on the center rack and heat until the pan is very hot, about 15 minutes.

In a medium bowl, combine the chimichurri ingredients and stir. Allow to stand at room temperature for 20 minutes or so. The recipe will make 3/4 cup; save the remainder for other dishes.

Meanwhile, separate the turnips from their greens. Give the greens a thorough washing and chop. In a medium bowl, toss the turnips with the olive oil and season with salt and pepper.

Add the turnips to the hot pan and roast until just softened, 4 to 6 minutes, depending on the size.

Place the pan on stove top over medium-high heat, stir in the turnip greens, and sauté briefly. Add 2 Tbsp of the stock, followed by 1/4 cup of chimichurri, and stir to combine. Add up to the remaining 2 Tbsp stock if you need to loosen the sauce. Taste and adjust the seasoning.

Transfer to a serving platter, squeeze on the lemon juice, Serve warm.